The present invention relates to a method of purifying waste waters with treated aluminum oxides.
In view of the great emphasis being placed upon waste water purification it is very important that sorbents and the like be used which are effective yet simple and economical to use.
Although activated carbon has been suggested as an adsorption agent for water purification, it has proven to be rather expensive. Furthermore, use of the carbon naturally results in a portion of its activity when thermally regenerated as well as a portion of the carbon being carried away with the purified waste water. Additionally, activated carbon adsorbs higher molecular weight substances to a lesser degree, thus making the purfication more expensive.
Pure aluminum oxide has previously been suggested as a waste water purification agent. These agents are supposed to be relatively effective in purifying water containing organic waste compounds which are strongly polar and which cannot satisfactorily be purfied with activated carbon. In particular, the KMnO.sub.4 active lignin containing products of sulfite cellulose manufacturing waste waters can be adsorptively removed by means of aluminum oxide.
However, pure aluminum oxide, compared with activated carbon has a lesser purification capacity and a less broad spectrum of application. In particular, pure aluminum oxide has proven to be relatively ineffective in adsorbing neutral substances and basic compounds thus presenting a problem because waste waters contain wide varieties of substances. The term "neutral substances" refers to non-polar substances having a p.sub.H of about 7 in aqueous solution.